1. A study was made of the effects of certain variables on the production of Avena coleoptiles that are straight and uniform in length at a specified age. 2. The results were utilized to devise a procedure for the production of consistently uniform coleoptiles. The suggested regimen follows: (a) Select uniform, large seeds from a single lot and husk and place in a desiccator at 85% relative humidity until they attain a constant weight. Humidification may be omitted under certain conditions (see text). (b) Soak seeds for 2 hours in aerated distilled water. Light has no effect during this period. (c) Plant seeds in growing boxes (described in text) and place in red light (4.1 ft-c. of wave lengths longer than 607 mμ) for 48 hours. (d) Transfer to complete darkness for 24 hours. (e) Maintain all temperatures at 22⚬C. (±1.0⚬).